Tuning an 'Ear' to the Music of Gravitational Waves

A team of scientists and engineers at NASA's Jet Propulsion Laboratory has brought the world one step closer to "hearing" gravitational waves -- ripples in space and time predicted by Albert Einstein in the early 20th century.

The research, performed in a lab at JPL in Pasadena, Calif., tested a system of lasers that would fly aboard the proposed space mission called Laser Interferometer Space Antenna, or LISA. The mission's goal is to detect the subtle, whisper-like signals of gravitational waves, which have yet to be directly observed. This is no easy task, and many challenges lie ahead.

The new JPL tests hit one significant milestone, demonstrating for the first time that noise, or random fluctuations, in LISA's laser beams can be hushed enough to hear the sweet sounds of the elusive waves.

"In order to detect gravitational waves, we have to make extremely precise measurements," said Bill Klipstein, a physicist at JPL. "Our lasers are much noisier than what we want to measure, so we have to remove that noise carefully to get a clear signal; it's a little like listening for a feather to drop in the middle of a heavy rainstorm." Klipstein is a co-author of a paper about the lab tests that appeared in a recent issue of Physical Review Letters.

The JPL team is one of many groups working on LISA, a joint European Space Agency and NASA mission proposal, which, if selected, would launch in 2020 or later. In August of this year, LISA was given a high recommendation by the 2010 U.S. National Research Council decadal report on astronomy and astrophysics.